34

‘population. The findings also support the program
of thyroxine replacement in che exposed Rongelap
population to prevent both clinical hypothyroidism andtheassociated rise in plasma TSH, which
may be tumorigenic.

wassignificantly lower (6.02°1.8 ug/dl). Thefrequency distribution calculations (see Table 29 and

Figure 39) indicate that a substantial portion ot
the Utirik population has plasma T, concentra-

don <5 yug/dl. Measurements of plasma tri-

iodothyronine (not shown) showed similar reductions in those patients with low T,4 values. Plasma

During the 1973 survey, T,4 and TSH concen-

40

trations were measured in plasma from 109 unexposed Rongelap and 97 exposed Utirik subjects
(see Table 29). The mean Ty, in the unexposed
Rongelap group, 7.7 ug/dl, was the same as in

March 1973

Group

109 Rongelap
unexposed
97 Uurik
exposed

Plasma T,,
pe/dl -

Subjects
with value
<5.0

Subjects
with value
>IL3

7.72.0

6%

6%

6.01.8"

32%**

6%

“Significantly different, 2<~0.001.
"*6% had values < 3.8.

T

]

7.5

10.0

12.5

RQ.
t

‘
‘
‘
‘
\

S
r

30

|

% oftatal pop ulation

Plasma Thyroxine Concentrations (Mean + 5.D.)
in Utirik and Unexposed Rongelap Populations,

]

March 1973

the plasma T.4 concentrations were skewedto the

Table 29

Tr

e-—e Rongelap

the United States, and, as in the United States,

upper range. In the Utirik group, the mean Ty

T

e---e8 Utirik

[ws

4. Thyroid Function in the Utirik and
Unexposed Rongeiap Groups

10

25

30

Plasma thyroxine (2¢/100 ml)

Figure 39. Percentages of people in Utirik and in Rongelap unexposed groups having given thyroxinelevels, 1973.

Table 30

Thyroxine-Binding Globulin (TBG) Levels
(Mean = S.D.) in Serum, 1973
TBG by RIA
Group

Rongelap

Exposed
Unex
All sera
All sera*

Uurik

All sera

_ Allsera*

capacity

mg/dl

n

pg T,/dl

12
13
29
22

1.450.354
1.822-1.22
1.64+0.95
1.340.45

14
1400
25
21

21.52 69
-25.32215.7
«23.1 ths
IS.1= 62

22

1.400.42

1.40--0.42

a

TBG-binding

n

22

T'BG capacity
—

31

27)

18.9 78

«16.4 43

*Omicting sera with TBG>3 or TBG-binding capacity
> 30.

Statistical comparisons revealed no significant differ-

ence ( p>0.05) berween any of the groups.

J0bet oI

Figure 40. Thyroxine-binding globulin levels

in serum and TBG-binding capacity, 1973.

4|
|
4

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